This plugin hasnt been tested with the latest three major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

Retina Image File Size + Mobile

If you’re running a Click Arbitrage site or target Mobile devices, which
may be on 3G networks or simply have under powered CPUs or little memory.

This occurs as size of Retina images eat up all your visitor’s connection
bandwidth, then require heavy CPU + memory usage to render.

Retina Image 404s On Server

Most sites serving Retina images, do so via the horribly simplistic retina.js library.

Unfortunately this script works by…

1) Extracting every DOM tag + rewriting the URL as
image-name@2X.extension back into the DOM.

2) For many sites 100% of these image-name@2X.extension file access
result in a 404 (missing page) error. Then retina.js will walk
the DOM again, removing the @2X from images + the image file
fetch begins again. Since this process runs via AJAX, instantaneously
page load resource usage can spike very high.

3) WordPress caching plugins specifically avoid caching 404 errors. This
is intentional. The idea being, once you notice 404s, you’ll fix them.
If 404s were cached, every permanent + transient 404 error would
require a manual cache flush, to clear the cache object, so the fixed
page could then reach visitors.

4) Thus every 404 @2X image served generates what tends to be an extremely
high resource intensive page view… all for nothing…

5) If you have 20 images on a page you’ll generate 20x 404s.

You can see when this can lead to extreme dips in performance,
which are hard to diagnose, unless you have a Server Savant
doing daily log studies with logtop to monitor page view patterns.

Some servers where I host client sites showed 90%+ of all page
accesses were 404s to Retina images.